2.2 Group 2

• What is the trend in atomic radius in group 2?

  Increases down the group as extra shells
• how does 1st IE change down group 2?

  - decreases

  - extra shells added

  - more shielding hence weaker attraction between the nucleus and outer electrons

  - outer electrons are further from the nucleus which weakens attraction

  - both of these make it easier to remove the outer electron and so less energy is needed to remove the outer electron
• How does melting point change down group 2?

  - decreases

  - size of metal ion increases but the number of delocalised electrons and charge remains the same

  - larger ions means the distance between the positive nuclei in metal atoms and delocalised electrons is greater which therefore weakens the attractive force

  - this makes it easier to break bonds and hence less energy required which leads to lower melting points
• How do group 2 elements react with water?

  - Form metal hydroxides (which are bases) and hydrogen gas

  - reactive increases with water

  - atom gets larger and electron is further from nucleus. Easier to remove and hence more reactive. There is more shielding
• What is the exception with Mg and water?

  Mg reacts slowly with cold water but more vigorously with steam. This produces MgO instead of a hydroxide
• How does group 2 hydroxide solubility vary down the group?

  Increases with barium hydroxide being the most soluble
• How does group 2 sulphates solubility vary down the group?

  Decreases
• How can you test for sulphates?

  Using BaCl2

  1. Add HCl to remove any carbonates. These could give a false positive

  2. Add barium chloride - forms white precipitate
• Give the ionic and general equation to show the formation of barium sulphate from barium chloride

  Ba2+ + So42- -> BaSO4

  BaCl2 + ZnSO4 -> BaSO4 + ZnCl2
• What is calcium hydroxide used for?

  Neutralising acidic soils
• What is magnesium hydroxide used for?

  Neutralising excess stomach acids
• What is the ionic equation for neutralisation?

  H+(aq) + OH-(aq) --> H2O(l)
• What is barium sulphate used for?

  To help identify problems with the digestive tract in a barium meal
• Why is bariumn sulphate used if its toxic?

  It is insoluble and therefore can't be absorbed into the blood
• What is magnesium used for? Give an equation

  To extract titanium

  TiCl4 + 2Mg -> Ti + 2MgCl2
• How is sulphur dioxide emissions removed?

  Using calcium carbonate in a process called wet scrubbing to neutralise SO2 in flue gases